### Please describe the problem.
I tried git annex init on a worktree checkout of a branch, but got an error (see below).
The worktree is for a repo that is itself a submodule of another repo.

### What steps will reproduce the problem?
I can try later to make an isolated reproducible example, but I think the above scenario describes it.

### What version of git-annex are you using? On what operating system?

[[!format sh """
[bpb23-acc /data/ilya/iwork/marti/tmp/wtree/is-231002-1155-marti-cpp]$ git annex version
git-annex version: 10.20230626-g801c4b7
build flags: Assistant Webapp Pairing Inotify DBus DesktopNotify TorrentParser MagicMime Benchmark Feeds Testsuite S3 WebDAV
dependency versions: aws-0.22 bloomfilter-2.0.1.0 cryptonite-0.29 DAV-1.3.4 feed-1.3.2.0 ghc-8.10.7 http-client-0.7.9 persistent-sqlite-2.13.0.3 torrent-10000.1.1 uuid-1.3.15 yesod-1.6.1.2
key/value backends: SHA256E SHA256 SHA512E SHA512 SHA224E SHA224 SHA384E SHA384 SHA3_256E SHA3_256 SHA3_512E SHA3_512 SHA3_224E SHA3_224 SHA3_384E SHA3_384 SKEIN256E SKEIN256 SKEIN512E SKEIN512 BLAKE2B256E BLAKE2B256 BLAKE2B512E BLAKE2B512 BLAKE2B160E BLAKE2B160 BLAKE2B224E BLAKE2B224 BLAKE2B384E BLAKE2B384 BLAKE2BP512E BLAKE2BP512 BLAKE2S256E BLAKE2S256 BLAKE2S160E BLAKE2S160 BLAKE2S224E BLAKE2S224 BLAKE2SP256E BLAKE2SP256 BLAKE2SP224E BLAKE2SP224 SHA1E SHA1 MD5E MD5 WORM URL X*
remote types: git gcrypt p2p S3 bup directory rsync web bittorrent webdav adb tahoe glacier ddar git-lfs httpalso borg hook external
operating system: linux x86_64
supported repository versions: 8 9 10
upgrade supported from repository versions: 0 1 2 3 4 5 6 7 8 9 10
local repository version: 10
(pbase-025-env) Wed 15 Nov 2023 01:37:24 PM EST
[bpb23-acc /data/ilya/iwork/marti/tmp/wtree/is-231002-1155-marti-cpp]$ uname -a
Linux bpb23-acc 5.4.0-136-generic #153-Ubuntu SMP Thu Nov 24 15:56:58 UTC 2022 x86_64 GNU/Linux
(pbase-025-env) Wed 15 Nov 2023 01:37:25 PM EST
[bpb23-acc /data/ilya/iwork/marti/tmp/wtree/is-231002-1155-marti-cpp]$ 
"""]]

### Please provide any additional information below.

[[!format sh """
# If you can, paste a complete transcript of the problem occurring here.
# If the problem is with the git-annex assistant, paste in .git/annex/daemon.log
[bpb23-acc /data/ilya/iwork/marti/tmp/wtree/is-231002-1155-marti-cpp]$ git annex init
init  
git-annex: worktrees/is-231002-1155-marti-cpp/info/attributes: openFile: does not exist (No such file or directory)
failed
init: 1 failed


# End of transcript or log.
"""]]

### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)
Well I keep coming back to it as a solution :)  Right now I'm trying to set up proper test cases for a tool that processes sequencing data, and even moderate-size test files break github's size limits.  I'm also planning to demo git-annex to others in my group so they can start using it.

